ipad mini
How to wipe out my current ipad mini to create a new user.
iPad mini, iOS 9
Question marked as
Follow these instructions:--> What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
When done, your device is ready to be used as if it were brand new.
But if you don't know the existing Apple ID & Password, you won't be able to perform the above process.
Regards
Giulio